Photoelectronic Properties Research Articles

0D/2D MXene Quantum Dot/Ni-MOF Ultrathin Nanosheets for Enhanced N2 Photoreduction

To improve the photocatalytic efficiency of the N₂ reduction reaction, MXene quantum dots (Ti₃C₂-QDs) and two-dimensional (2D) nickel metal–organic framework (Ni-MOF) with different ratios were fabricated by a simple self-assembly strategy to form type II heterojunctions. The resultant composites showed enhanced absorption and excellent interfacial charge-transfer capabilities according to the optical and photoelectron properties. The optimal Ti₃C₂-QD/Ni-MOF heterostructure exhibited a considerable ammonia yield rate (88.79 μmol gcₐₜ–¹ h–¹). By means of X-ray absorption near-edge fine structure (XANES) technique, it was found that the interaction of Ti₃C₂-QD and Ni-MOF could accelerate the electron transfer, and Ni site would be the main area to enrich the electron density as well as adsorb and activate N₂. Finally, with the aid of density functional theory (DFT) calculations and in situ Fourier transform infrared spectrometry (FTIR), the reaction pathway and intermediate products were studied.

Iridium Complexes Embedding Rigid D-A-Type Coordinated Cores: Facile Synthesis and High-Efficiency Near-Infrared Emission in Solution-Processed Polymer Light-Emitting Diodes

Two near-infrared (NIR)-emitting iridium(III) complexes of (Me-BIPz)2Ir(acac) and (tBu-BIPz)2Ir(acac), (i.e. Ir-1 and Ir-2) are designed and synthesized, which contain methyl and t-butyl substituted 14-phenyl-14H-benzo[a]indolo[3,2-c]phenazine (BIPz), respectively with a rigid D-A-type coordinated core. The influence of the rigid D-A skeleton and the attached groups on photoelectronic properties of iridium complexes is primarily investigated. An advanced external quantum efficiency (EQE) of 2.65% with a radiant emittance of 13057 mW Sr−1 m−2 at 746 nm is obtained in the Ir-2-doped polymer light-emitting devices. This EQE value is 1.5 times higher than that in the Ir-1-doped devices. Furthermore, this type of iridium complexes exhibits better NIR-emitting properties than most of the reported iridium complexes containing the C^N ligand with two coordinated aryl rings. The results indicate that the rigid coordinated core of C^N ligand is an effective strategy to construct high-efficiency NIR-emitting iridium complexes.

Enhancing the efficiency of Sb2S3 solar cells using dual-functional potassium doping

Antimony sulphide (Sb2S3) thin films have attracted considerable research interest as a photovoltaic absorber material owing to their suitable band gap, large absorption coefficient, and excellent photoelectronic properties. In this study, cadmium sulphide (CdS) films were doped with potassium, which increased their crystallinity and optical transmission. These films were then used as a buffer layer to increase the efficiency of Sb2S3 solar cells. Furthermore, the potassium diffused into the Sb2S3 film, which increased their crystallinity and light absorption and decreased its surface roughness. Dual-functional potassium doping helped improve all of the photoelectric parameters of the Sb2S3 solar cells. Specifically, the device efficiency increased from 4.57% to 6.53% (an increase of 42.89%), and a high current density of 15.29 mA cm−2 was achieved. These findings are expected to facilitate the further development of Sb2S3 thin-film solar cells for industrial applications.

Photoelectrochemistry of Poly‐3‐hexylthiophene and Stannum Chromium Bimetallic Nanoparticle Heterojunction Blend

AbstractIn the design and fabrication of photovoltaic cells, acceptors are as important as donors. Quite a large variety of donors exist while most common acceptors are fullerene based and these acceptors are limited in properties. Herein we report the design, optoelectronic and photoelectrochemical properties of three new stannum‐based bimetallic nanoparticles (SnTi, SnV and SnCr) combined with poly(3‐hexylthiophene)(P3HT) as electron donor material in the fabrication of bulk heterojunction photovoltaic cells. SnCr nanoparticles displayed excellent electrocatalytic and photoelectronic properties. Solar cell device constructed with P3HT as donor and SnCr as acceptor achieved an open circuit voltage ca. 1 V and efficiency 1.46 %.

Optical and photoelectronic properties of a new material: Optoelectronic application

Optical and photoelectronic properties of a new material: Optoelectronic application

Advanced Functional Electroactive and Photoactive Materials for Monitoring the Environmental Pollutants

AbstractFunctional materials with attractive electronic and photoelectronic properties show great promise in various fields. In recent decades, tremendous research efforts have been devoted to the design of photoactive and electroactive materials for qualitative and quantitative analysis of environmental pollutants. This review gives a concise overview on the fundamentals and recent research progress of functional material‐based electrochemical and photoelectrochemical technology for environmental pollutant monitoring. The rational design of functional photoactive and electroactive materials with promoted electrochemical properties and basic signaling strategies for electrochemical and photoelectrochemical sensors are presented. Based on these insights, very recent achievements for electrochemical and photoelectrochemical environmental pollutant sensors are summarized from the viewpoint of various functional materials. At last, critical challenges and future research perspectives in this field are proposed and discussed to provide a backdrop for future research.

Perovskite Nanocrystals‐Based Heterostructures: Synthesis Strategies, Interfacial Effects, and Photocatalytic Applications

Perovskite nanocrystals (PNCs) have recently emerged as a new type of promising photocatalytic semiconductor due to their unique photoelectrochemical properties, including tunable bandgap and crystal structure, entire visible spectral response, and versatile chemical processability. However, under practical circumstance, this type of pure‐phase PNCs photocatalyst demonstrates poor stability, limited light utilization, and high carrier recombination, resulting in low solar power conversion efficiency and inferior catalytic activity. To address these issues, extensive research efforts have been devoted to developing PNCs‐based heterostructures. Thus, a perspective on the development of PNCs‐based heterophotocatalysts is timely. In this Review, the progress of PNCs‐based heterophotocatalysts is presented starting from fundamental properties (i.e., crystal and bandgap structure, photoelectronic properties, etc.) to state‐of‐the‐art applications with a focus on stability improving, dispersion enhancing, and interfacial charge carrier dynamic optimizing. Critical insights are further provided into the existing challenges and prospects for high‐quality PNCs‐based heterostructures in advanced photocatalytic applications.

Nanostructured Microspheres Based on Titanium Nano-Oxide with the Function of Accumulation of a Charge for Prolonged Catalysis

Nanoheterostructures based on titanium, vanadium, molybdenum, and tungsten oxides assembled in the form of microspheres have been synthesized. Their structural and photoelectronic properties have been studied. It has been shown that the photocatalysis rate increases significantly for microspheres consisting several metal oxides. A relation of the photocatalysis rate to the number of V4+ paramagnetic centers and the time of their relaxation after the end of illumination has been revealed. It has been found that the spatial separation of photoexcited charge carriers between different nano-oxides in heterostructures leads to the accumulation of charge in them and to prolonged catalysis. Consequently, they are promising for application as the main material of photocatalytic filters for cleaning the environment.

(Invited) Nanostructured Conjugated Materials in Metal-Organic Frameworks

As conjugated polymers play crucial roles in advanced nanoscale devices, future applications require a deeper understanding optoelectrical properties of conjugated polymers in low-dimensional assemblies. Confinement of polymer chains in nanoporous materials is a feasible method to control the polymer assemblies because this approach can prevent the entanglement and conformational disorder of polymer chains in the bulk state. The regulated and tailor-made pore characteristics of metal-organic frameworks (MOFs) allow the achievement of precise molecular assemblies in the nanopores, permitting fundamental studies on polymer properties that, until now, have remained elusive.1 Here, we report that the hybridization of MOFs and polythiophene (PTh) provides a great insight into inherent optoelectrical properties of PTh as well as functional nanomaterials for electronics and sensors.2 Controlled assembly of PTh donor and acceptor molecules is a key structure for photovoltaics and photocatalysis. We also demonstrated that unique interfaces between PTh and acceptor molecules, such as fullerene and titanium oxide, mediated by MOFs, enabled remarkable photoelectronic properties superior to conventional PTh systems.3 Other than conjugated polymers, a variety of conjugated materials, including graphene nanoribbons, could be prepared in MOFs, providing distinctly properties to those prepared in the bulk state because of the formation of specific assemblies.4 REFERENCES1. Chem. Soc. Rev. 2017, 46, 3108.2. (a) J. Am. Chem. Soc., 2015, 137, 5231. (b) Angew. Chem. Int. Ed., 2016, 55, 708. (c) Polym. Chem., 2017, 8, 5077. (d) Eur. Polym. J., 2018, 109, 162. (e) J. Am. Chem. Soc., 2019, 141, 19565.3. (a) Nat. Commun., 2018, 9, 1660. (b) J. Phys. Chem. C, 2018, 122, 24182.4. J. Am. Chem. Soc., 2020 , 142, 5509. Figure 1

High-performance infrared Ge-based plasmonic photodetector enhanced by dual absorption mechanism

A sub-wavelength plasmonic Au–Ge grating was used to enhance the responsivity of Ge-based metal–semiconductor–metal photodetectors at infrared communication wavelengths. Furthermore, a finite-difference time-domain simulation was performed to optimize absorption of light by the detectors. Characterizations of the photoelectronic properties of the optimized device revealed high-performance photodetection with a responsivity of 0.38 A/W and an external quantum efficiency of 30% for 1.55 μm wavelength incident light. Moreover, an enhancement peak across three infrared telecommunication bands (C-band, L-band, and U-band) was achieved in the plasmon-enhanced photodetector. According to the simulation results of the optical absorption spectra, the distributions of electric field, and absorbed power, the enhancements of responsivity and quantum efficiency could be ascribed to the surface plasmons at the Au/Ge interface. These plasmons boosted inter-band transition and internal photoemission effect simultaneously, enabling high efficient photodetection around the C-band. The results of the fabricated devices demonstrated the potential of this approach for achieving high-performance Ge-based photodetectors.

Hydrothermal syntheses, structures and properties of a series of new hybrid iodometallates containing rare cross-shaped spirobifluorene derivatives

A series of new hybrid iodometallates [H4Spiro-4-py]n[Cu7I10]n(I3−)n·0.5(I2)n·nH2O (1), [Cu2I2(Spiro-3-py)]n·0.75n(DMF)·0.25nH2O (2), [H2Spiro-4-py][H3Spiro-4-py][Ag10I20]0.5·H2O (3) and [H2Spiro-4-py]n[H3Spiro-4-py]n[Ag8I13]n·2.5H2O (4) were hydrothermal synthesized. 1 contains 1-D chain [Cu7I10]n based on new [Cu7I12] cluster, free I3− anions and I2 molecules, which are interconnected by weak I⋯I interactions to generate a novel polyiodide {[Cu7I10](I3−)·(I2)}n framework. 2 features a neutral sql layer [Cu2I2(Spiro-3-py)]n constructed by the interconnection of the {Cu2I2} dimers and Spiro-3-py ligands. The anionic [Ag10I20]10− framework of 3 can be described as an aggregation of two tetrameric [Ag4I8] clusters and one dimeric [Ag2I6] unit via sharing corner. The 1-D anionic chain [Ag8I135−]n of 4 is built up from the alternate connection of tetrameric [Ag4I8] units and rare larger [Ag12I20] clusters, which offers the only example of 1-D iodoargentates based on two types of iodoargentate clusters. The optical and photoelectronic properties of all compounds were also investigated.

Toward Efficient and Stable Perovskite Solar Cells: Choosing Appropriate Passivator to Specific Defects

With a certificated record efficiency of 25.2%, organometal halide perovskite (OHP) solar cells have experienced unprecedentedly rapid development in the past decade due to their extraordinary photoelectronic properties. However, because of the rapid processing conditions and complex precursor compositions, there are a large number of defects in polycrystalline OHP films, including point defects and 2D defects along grain boundary and on the surface. Unfortunately, these defects serve as the nonradiative recombination centers and exert negative effects on the degradation and performance of OHP layers, heavily limiting their further application for efficient photovoltaic devices. Herein, the formation origin of various defects as well as their detrimental effects on the efficiency and stability of perovskite solar cells (PSCs) are discussed, and recent passivation strategies for specific defects to minimize defect state density in the perovskite films are summarized. Finally, a brief outlook on the development trend of future passivation engineering is provided for deeper understanding of efficient and stable PSCs.

Screening metal-dicorrole-based dyes with excellent photoelectronic properties for dye-sensitized solar cells by density functional calculations

The dye molecules behaving as photosensitizers in dye-sensitized solar cells are the most critical factors to determine the power conversion efficiency. Therefore, ways to design dye molecules with excellent photoelectric properties has been the focus of dye-sensitized solar cells research. Here, we selected four representative different metal-corrole monomers to characterize their structures and photoelectronic properties. Then based on these metal-corrole monomers, six different architectures of metal-dicorroles were designed by varying the linking forms. The most stable architecture [Formula: see text] was screened out by binding energy calculations. A further two types of metal-dicorrole-based dyes were constructed by incorporating different bridge groups with the cyanoacry acceptor into the stable metal-dicorroles. A large number of density functional theory calculations and photoelectric properties analysis indicate that among these different metal-dicorrole-based dyes, Ga-dicorrole dyes have two strong and wide absorption bands in the visible region corresponding to Soret and Q bands, respectively, and have high charge separation efficiency under optical excitation. Especially for Ga-SN dye, by incorporating a [Formula: see text]-bridge-conjugated group, its Soret absorption band is greatly enhanced, broadened and red-shifted, resulting in its merging with the Q band into one absorption band. Moreover, its charge transfer efficiency is up to 76.86%, which will facilitate its coupling with semiconductor materials and transfer its electrons to the semiconductor materials.

Anchoring Zn-phthalocyanines in the pore matrices of UiO-67 to improve highly the photocatalytic oxidation efficiency

Metallophthalocyanines (MPcs) with unique photoelectronic properties are a class of very promising photosensitizers for highly efficient photocatalysis; however, their photocatalytic applications are heavily frustrated by the strong π-π self-aggregation issue. We report herein a partial ligand substitution strategy to imbed MPcs in the pore matrices of metal-organic frameworks (MOFs), which could significantly improve the photocatalytic efficiency of MPcs by prohibiting their cofacial self-aggregation. We successfully incorporate ZnPc moieties into the pore matrices of MOF UiO-67 by partially replacing the pristine 4,4′-biphenyldicarboxylate (BPDC) ligands with four-branched ZnPc ligands, in which the ZnPc photosensitizers are easily accessed to reactant molecules in photocatalysis by taking the advantages of porous MOF UiO-67. The ZnPc-incorporated MOF UiO-67-ZnPc demonstrates high photocatalytic efficiency and selectivity in aerobic oxidation of naphthols to produce highly value-added naphthoquinones with high photoactivity, stability and broad substrate applicability under visible light irradiation, which is much superior to its molecular counterpart.

Recent advances in metal halide perovskite photocatalysts: Properties, synthesis and applications

Metal halide perovskites (MHPs) are a special class of photocatalysts that exhibit excellent performance in photocatalysis. This review gives a comprehensive overview of their recent advances. • Metal halide perovskites (MHPs) are a special class of photocatalysts. • Fundamental features and synthesis methods of MHP photocatalysts are introduced. • Recent advances of MHP-based photocatalytic reactions are systematically reviewed. • The challenges and outlook for the MHP photocatalytic systems are proposed. As a class of new emerged semiconductors, MHPs exhibit many excellent photoelectronic properties, which are superior to most conventional semiconductor nanocrystals (NCs). Particularly, MHPs have received extensive attention and brought new opportunities for the development of photocatalysis. Over the past few years, numerous efforts have been made to design and prepare MHP-based materials for a wide range of applications in photocatalysis, ranging from photocatalytic H 2 generation, photocatalytic CO 2 reduction, photocatalytic organic synthesis and pollutant degradation. In this review, recent advances in the development of MHP-based materials are summarized from the standpoint of photocatalysis. A brief outlook of this field has been proposed to point out some important challenges and possible solutions. This review suggests that the new family of MHP photocatalysts provide a new paradigm in efficient artificial photosynthesis.

Optical, electronic and visible-range photo-electronic properties of boron carbide-indole films

Semiconducting aromatic boron carbide films have been formed by plasma enhanced chemical vapor deposition (PECVD) from closo-1,2-dicarbadodecarborane (orthocarborane) and indole precursors. X-ray photoemission and ellipsometry indicate that the films consist of intact indole moieties bonded to the B sites on orthocarborane icosahedra. The ellipsometry measurements, of the PECVD hydrogenated boron carbide alloyed with indole moieties, indicate indirect and direct band gaps of 1.6 eV and 3.5 eV, respectively, in good agreement with density functional theory cluster calculations. These calculations also indicate that states near the valence band maximum and conduction band minimum are associated with indole and carborane moieties, respectively. The current versus voltage (I(V)) curves, of PECVD hydrogenated boron carbide alloyed with indole moieties to n-type silicon diodes, indicate a photocurrent at zero bias, with an appreciable open-circuit voltage of 1 V. The 4th quadrant conductivity and voltage, at the maximum power point, were 1.66 μA and 0.69 V respectively, under illumination. The frequency- and bias-dependent capacitance versus voltage (C(V)) data yield mean carrier lifetimes from 2.5 ms to 1.5 ms at low and high bias, respectively at 10 kHz, but falling to 0.5 ms, independent of bias voltage, at 100 kHz.

Twin-ZnSe nanowires as surface enhanced Raman scattering substrate with significant enhancement factor upon defect.

Semiconductor-based surface enhanced Raman scattering (SERS) substrate design has attracted much interest due to the excellent photoelectronic and biochemical properties. The structural change caused by twin in semiconductor will have an influence on improving the Raman signals enhancement based on the chemical mechanism (CM). Here, we demonstrated the twin in semiconductor ZnSe nanowires as an ultrasensitive CM-based SERS platform. The SERS signals of the rhodamine 6G (R6G) and crystal violet (CV) molecules adsorbed on twin-ZnSe nanowires could be easily detected even with an ultralow concentration of 10-11 M and 10-8 M, respectively, and the corresponding enhancement factor (EF) were up to 6.12 × 107 and 3.02 × 105, respectively. In addition, the charge transfer (CT) between the twin-ZnSe nanowires and R6G molecule has been demonstrated theoretically with first-principles calculations based on density-functional theory (DFT). These results demonstrated the proposed ZnSe nanowires with twin as SERS substrate has a broader application in the field of biochemical sensing.

Observation of two-level defect system in amorphous Se superlattices

Amorphous Se is a well-known photoconductor from its early applications in xerography and ultra-sensitive photodetectors like the High-gain Avalanche Rushing Photoconductor (HARP) device. The established way of fabricating the photoconductor for the HARP is rotational thermal evaporation using multilayers of Se and As2Se3. However, the electronic effects of multilayering have not yet been clarified. In this report, we investigated the multilayer structure as a superlattice of Se and As2Se3 fabricated using rotational evaporation and show that the superlattice structure results in the uniformization of the defect levels in the base materials. We found four energy levels associated with defects in As2Se3 and three levels in amorphous Se. In comparison, the superlattice structure of the two materials shows two clear energy levels at EC,Se − 0.533 eV and EV,Se + 0.269 eV. The resulting two occupied energy levels explain the photoelectronic and transport properties observed in multilayer amorphous Se. This result “reinvents” the multilayer structure as a material with observed quantum effects, which significantly improves the material performance in photodetection.

Tuning the optical properties of colloidal Quantum Dots using thiol group capping agents and its comparison

Mercapto Succinic Acid (MSA), Mercapto Propionic Acid (MPA) and Thio Glycolic Acid (TGA) capped Cadmium Telluride Quantum Dots (CdTe QDs) were synthesized by aqueous phase method. The growth mechanisms of the prepared CdTe QDs were observed to be dependent on the molecular structure of the surfactants used, which in turn had impact on the CdTe QDs growth kinetics, size and shape. The functional groups attached to the surfactant were found to get influenced by the diffusion length, electron confinement and charge transfer. Henceforth, the photo physical and electronic properties of these CdTe QDs were also determined by its molecular structure. In addition, the refluxing time during the synthesis played a significant role in defining the CdTe QDs size and its luminescence effect. Based on the selection of surfactants, the luminescence property of CdTe QDs can be altered, which will make these materials a suitable candidate for extensive variety of applications. Using UV–Visible and Photo Luminescence spectrum the growth kinetics of the CdTe QDs with three different capping agents has been explored first time and this can be utilized for different applications.

HI hydrolysis-derived intermediate as booster for CsPbI3 perovskite: from crystal structure, film fabrication to device performance

Nowadays, inorganic CsPbI3 perovskite solar cells (PSCs) have become one of the most attractive research hotspots in photovoltaic field for its superior chemical stability and excellent photo-electronic properties. Since the first independent report in 2015, the power conversion efficiency (PCE) of CsPbI3 based PSCs has sharply increased from 3.9% to 19.03%. Importantly, during the developing process of CsPbI3 PSCs, HI hydrolysis-derived intermediate plays an important role: from stabilizing the crystal structure, optimizing the fabricated film to boosting the device performance. In this review, the different crystal and electronic structures of CsPbI3 are introduced. We then trace the history and disputes of HI hydrolysis-derived intermediate to make this review more logical. Meanwhile, we highlight the functions of HI hydrolysis-derived intermediate, and systematically summarize the advanced works on CsPbI3 PSCs. Finally, the bottlenecks and prospects are revealed to further increase the CsPbI3 PSCs performance.